mirror of
https://github.com/mozilla/gecko-dev.git
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102 lines
3.2 KiB
C++
102 lines
3.2 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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// This file should only be compiled if you're on Power ISA.
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#include "nscore.h"
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#include "nsTextFragmentImpl.h"
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#include "mozilla/Assertions.h"
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#include <algorithm>
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#include <altivec.h>
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namespace mozilla {
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namespace VMX {
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int32_t FirstNon8Bit(const char16_t* str, const char16_t* end) {
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const uint32_t numUnicharsPerVector = 8;
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const uint32_t numCharsPerVector = 16;
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// Paranoia. If this assertion is wrong, change the vector loop below.
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MOZ_ASSERT((numCharsPerVector / numUnicharsPerVector) == sizeof(char16_t));
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typedef Non8BitParameters<sizeof(size_t)> p;
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const uint32_t alignMask = p::alignMask();
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const size_t mask = p::mask();
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const uint32_t numUnicharsPerWord = p::numUnicharsPerWord();
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const uint32_t len = end - str;
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// i shall count the index in unichars; i2 shall count the index in chars.
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uint32_t i = 0;
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uint32_t i2 = 0;
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// Align ourselves to a 16-byte boundary, as required by VMX loads.
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uint32_t alignLen = std::min(
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len, uint32_t(((-NS_PTR_TO_UINT32(str)) & 0xf) / sizeof(char16_t)));
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if ((len - alignLen) >= numUnicharsPerVector) {
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for (; i < alignLen; i++) {
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if (str[i] > 255) return i;
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}
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// Construct a vector of shorts.
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#if __LITTLE_ENDIAN__
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const vector unsigned short gtcompare =
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reinterpret_cast<vector unsigned short>(
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vec_mergel(vec_splat_s8(-1), vec_splat_s8(0)));
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#else
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const vector unsigned short gtcompare =
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reinterpret_cast<vector unsigned short>(
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vec_mergel(vec_splat_s8(0), vec_splat_s8(-1)));
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#endif
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const uint32_t vectWalkEnd =
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((len - i) / numUnicharsPerVector) * numUnicharsPerVector;
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i2 = i * sizeof(char16_t);
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while (1) {
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vector unsigned short vect;
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// Check one VMX register (8 unichars) at a time. The vec_any_gt
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// intrinsic does exactly what we want. This loop is manually unrolled;
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// it yields notable performance improvements this way.
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#define CheckForASCII \
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vect = vec_ld(i2, reinterpret_cast<const unsigned short*>(str)); \
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if (vec_any_gt(vect, gtcompare)) return i; \
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i += numUnicharsPerVector; \
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if (!(i < vectWalkEnd)) break; \
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i2 += numCharsPerVector;
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CheckForASCII CheckForASCII
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#undef CheckForASCII
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}
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} else {
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// Align ourselves to a word boundary.
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alignLen = std::min(len, uint32_t(((-NS_PTR_TO_UINT32(str)) & alignMask) /
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sizeof(char16_t)));
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for (; i < alignLen; i++) {
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if (str[i] > 255) return i;
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}
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}
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// Check one word at a time.
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const uint32_t wordWalkEnd =
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((len - i) / numUnicharsPerWord) * numUnicharsPerWord;
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for (; i < wordWalkEnd; i += numUnicharsPerWord) {
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const size_t word = *reinterpret_cast<const size_t*>(str + i);
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if (word & mask) return i;
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}
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// Take care of the remainder one character at a time.
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for (; i < len; i++) {
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if (str[i] > 255) {
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return i;
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}
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}
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return -1;
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}
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} // namespace VMX
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} // namespace mozilla
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